My understanding is whey protein is just that, unrefined whey protein. WPC is the next refining step that ranges from like 30-89%. Not sure if it goes lower than 30. Any refinement 90% and above is isolate. The lower end concentrates are around .40cents per pound! That's why manufacturers put proprietary blend in the ingredients. Then in () they list all the proteins. The proteins in the () do no need to be in order of greater amount like the rest of the ingredients because it is a proprietary blend. So WATCH out for proteins that list WPC last that also list WPI. Last does not mean least amount and why would they need WPC if they have WPI? It is the same protein just a different purity. It is because they want to put cheap as$ protein in to F@#K you!